This is a very confusing sentence on several levels.
The main character is the scumbag photojournalist, but why MUST he cover the tragedy? He can refuse an assignment; whats the worst that will happen? He'll get another one. Therefore it's not that he must cover the tragedy rather he simply covers it as? part of his job.
How does covering the death of a mostly unknown local person provide him his big break? If it were a senator or some other powerful person there would be merit to this claim, otherwise it doesn't make sense.
"...until the case becomes a homocide..." I'm sure you meant - homicide. Until it became a homicide, could be read that once the police change the cause of death to murder he will be assigned to a different story. Or do you mean that after the case was changed to homicide, his grandfather tries to persuade him? Punctuation or re wording could help with the specific meaning you're trying to convey.
As far as plot goes it is unclear what the story will be about. Is the inciting incident the police changing the case to homicide or the grandfather asking for help to frame someone else?
What is his goal? Is it to catch the killer? Is it to help the grandfather?
Why his grandfather? In what way and why, does the man's grandfather hold such a strong influence over him for it to be (as McKee would say) a story worthy problem?
Lastly if he is a scumbag photojournalist, why would the read/audience car about him? What is his redeeming quality that will make it worth their while investing emotionally in this man's story?